THRUSTING AND STRIKE-SLIP TECTONICS IN THE ALTO-MOLISE REGION (ITALY)- IMPLICATIONS FOR THE NEOGENE-QUATERNARY EVOLUTION OF THE CENTRAL APENNINE OROGENIC SYSTEM

The Alto Molise area belongs to the Apennine orogenic belt, which has been developing since the Late Cretaceous as a result of the Europe-Af rica collision. This area is characterized by the complex superpositio n of different palaeogeographic domains that developed during the Meso zoic along the passive southern margin of Tethys Ocean. These domains have been subdivided into four main structural units; from shallowest to deepest they are: the Sannio pelagic basin: the Latium-Abruzzi carb onate platform, the Molise pelagic basin and the Apulia carbonate plat form Units. Until the present study, the tectonic relationship among t hese units was thought to have been mainly determined by Early Messini an to Late Pliocene thrusting. This paper reports the results of a new geometric and kinematic analysis of the Alto Molise area. This new in terpretation of the Alto Molise structural style indicates that strike -slip tectonics played a primary role during post-Pliocene times, grea tly modifying the previous Alto Molise thrust structures. Two main tec tonic events are recorded, consisting of the Pliocene thrusting of the Molise domain onto the Apulia platform followed by the post-Pliocene disruption and rotation of the pre-existing compressional structures b y N-S-oriented, high-angle, right-lateral strike-slip faults. These fa ults are manifest in the Apulia platform as narrow shear zones, but pr opagate towards the surface into wider belts of strike-slip and obliqu e-slip deformation. We have compared our results with published struct ural, palaeomagnetic and anisotropy of magnetic susceptibility (AMS) d ata from the Central Apennines. This comparison suggests that the supe rposition of the younger strike-slip tectonic deformation on the older fold and thrust structures in the Alto Molise area is consistent with block-rotation of a segmented orogen, applied to the whole Apennine s ystem.